Solvent-based heavy oil recovery techniques can greatly enhance the recovery of heavy oil, extra-heavy oil and bitumen from subterranean reservoirs for both cold and hot applications. Cyclic and continuous injection of solvents reduces oil viscosity which increases oil production rates. Co-injection of solvent in a continuous or cyclic thermal EOR operation increases oil production rates, reduces steam requirements and may increase oil recovery. Solvent recovery is measured in the produced fluid stream to monitor processes and measure the amount of solvent that is recovered from the reservoir. Current methods for measuring the amount of solvent in such produced fluids are slow and sometime inaccurate. For example, the density of produced or monitored production fluids can be used to obtain rough estimates of the concentration of solvents in the production fluids.
Near-infrared spectroscopy (NIR) provides information on chemical and physical properties of sample components. Chemometric methods based on eigenvalue decomposition of a data matrix are effective tools for analyzing correlations between spectral information and compositions and properties. Principal component analysis (PCA) and partial least squares in latent variables (PLS) are commonly used techniques. NIR spectroscopy, in combination with chemometrics, is hence a powerful approach for fast routine and on-line chemical analyses.
A shortcoming of previous attempts to use NIR for analysis is that a plurality of components in a mixture of such components cannot be simultaneously analyzed as previous methods generally provide only analysis of one component at a time. Hydrocarbons and other liquids from several sources are often commingled. There is a need to determine the amount or content of these liquid mixtures of commingled fluids from several sources. This need is addressed by the present disclosure.